Control system and control method

ABSTRACT

A control system is provided that includes a power transmitting coil for wirelessly transmitting power supplied from a power source, a power receiving coil for wirelessly receiving power by electromagnetic coupling between the power transmitting coil and the power receiving coil, a driving circuit configured to drive a load portion using the power received via the power receiving coil, a transmitting coupler for wirelessly transmitting a transmission signal for controlling driving of the load portion, a receiving coupler for wirelessly receiving the transmission signal by electromagnetic coupling between the transmitting coupler and the receiving coupler, and a generation circuit configured to generate a driving signal for controlling the driving circuit from the transmission signal received via the receiving coupler.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/877,281, filed on May 18, 2020, which claims priority fromJapanese Patent Application No. 2019-097072 filed May 23, 2019, whichare hereby incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a control system that performs controlbased on wireless communication.

Description of the Related Art

Conventionally, there are systems that supply power to and drive motors.In a semiconductor exposure device, a motor that moves wafers by a verysmall amount in order to form patterns on the wafers is installed on astage for moving the wafers to an exposure position, and a power supplycable that supplies power for driving the motor is connected to thestage. This cable also moves as the stage moves, and thus, the tensionof this cable influences the positioning accuracy of the stage. In viewof this, consideration is being given to achieving wireless driving of amotor to remove the need for a power supply cable.

As a technique for achieving wireless driving of a motor, JapanesePatent No. 6219495 discloses a configuration of a motor system thatwirelessly drives a wheel of a vehicle. In this motor system, not onlyis power for driving a motor transmitted wirelessly, but a controlsignal is also transmitted to a motor driving circuit provided on apower-receiving side (movable side) by using wireless communicationutilizing electromagnetic waves, and control of the motor drivingcircuit is thereby realized. Furthermore, in order to deal with theinfluence of a delay that occurs when wireless communication utilizingelectromagnetic waves is performed, a detection circuit for detectingthe driving current and driving voltage is provided on thepower-receiving side and feedback control is performed based on detectedvalues, and control of a rectification circuit is thereby realized.

In recent years, there has been a demand to increase the speed ofwireless communication of a control signal for driving a load portion,such as a motor. In order to increase precision and exposure speed in asemiconductor exposure device for example, a control signal for drivingthe motor needs to be transmitted at a shorter cycle. In the techniquedisclosed in Japanese Patent No. 6219495, it can be expected that adelay of several hundred μs to several ms will occur due to protocolprocessing, etc., because radiative wireless communication utilizingelectromagnetic waves is performed in accordance with a standard ofwireless LAN, etc.

SUMMARY OF THE INVENTION

According to various embodiments of the present disclosure, a controlsystem is provided, which includes: a power transmitting coil forwirelessly transmitting power supplied from a power source; a powerreceiving coil for wirelessly receiving power by electromagneticcoupling between the power transmitting coil and the power receivingcoil; a driving circuit configured to drive a load portion using thepower received via the power receiving coil; a transmitting coupler forwirelessly transmitting a transmission signal for controlling the loadportion; a receiving coupler for wirelessly receiving the transmissionsignal by electromagnetic coupling between the transmitting coupler andthe receiving coupler; and a generation circuit configured to generate adriving signal for controlling the driving circuit from the transmissionsignal received via the receiving coupler.

Further features of the present disclosure will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit block diagram of a driving system according to oneembodiment.

FIG. 2 is a diagram illustrating circuit configurations of a motordriving circuit and a gate driving circuit according to a firstembodiment.

FIG. 3 is a schematic diagram illustrating an example in which thedriving system is applied to a movable stage according to oneembodiment.

FIG. 4 shows measurement results of input/output characteristics of thedriving system according to the first embodiment.

FIG. 5 is a diagram illustrating circuit configurations of the motordriving circuit and the gate driving circuit according to a secondembodiment.

FIG. 6 shows actually-measured results of operation waveforms of thedriving circuits according to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the attached drawings. Note that the followingdescribed embodiments are not intended to limit the scope of the presentdisclosure. Multiple features are described in the embodiments, but thepresent disclosure is not limited, for example, to embodiments thatrequire all such features, and multiple such features may be combined asappropriate. Furthermore, note that, in the attached drawings, the samereference numerals are given to the same or similar configurations, andredundant description thereof has been omitted.

First Embodiment

FIG. 1 illustrates a block configuration of circuits of a driving system300, which functions as a control system, according to the firstembodiment. The driving system 300 is constituted by a powertransmitting-side circuit 100 and a power receiving-side circuit 200.The power transmitting-side circuit 100 and the power receiving-sidecircuit 200 are not physically connected. Power is transmitted in acontactless manner from a power transmitting coil 101 to a powerreceiving coil 201, and control signals are transmitted in a contactlessmanner from a transmitting coupler 102 to a receiving coupler 202.

A power source 104 is a power source that drives a motor 400, which is aload portion. A controller 103, based on the current positioninformation of the motor 400, which can be obtained from an opticalsensor, etc., issues commands regarding the next position. Specifically,the controller 103 issues a command for an output voltage amplitudevalue of the power source 104 that determines the thrust of the motor400, and a command for a motor application voltage sign that determinesthe direction in which the motor 400 moves. The power source 104receives the command for the output voltage amplitude value from thecontroller 103, and outputs a voltage having an amplitude value based onthe command. The command for the motor application voltage sign (signswitching signal) is transmitted from the controller 103 to a gatedriving circuit 205 via a transmitting circuit 105, the transmittingcoupler 102, the receiving coupler 202, and a receiving circuit 203. Therectification operation of a motor driving circuit 206 is inverted by180° as described in the following by the sign switching signal, and thesign of the voltage applied to the motor 400 is inverted from positiveto negative or from negative to positive.

Operation of Driving System 300 for Application of Positive Voltage toMotor

First, an example of an operation of the driving system 300 for applyinga positive voltage to the motor 400 will be described in detail. Thepower source 104 having received the command for the output voltageamplitude value from the controller 103 outputs a voltage having anamplitude value based on the command (power source output voltage) to anSW circuit 106. The SW circuit 106 includes a generator that generates aclock signal of a predetermined frequency, and functions as a convertercircuit that performs switching on the input power source output voltage(DC voltage) by driving a switching element included in the SW circuit106 according to the generated clock signal, and converts the powersource output voltage (DC voltage) into an AC waveform (AC voltage). Theswitching frequency is higher than the command frequency of thecontroller 103, i.e., the motor control frequency. Note that the clocksignal may be generated by the controller 103 and supplied to the SWcircuit 106.

Then, the power output from the SW circuit 106 is transmitted to thepower transmitting coil 101, and is transmitted via the electromagneticcoupling between the power transmitting coil 101 and the power receivingcoil 201 and input to a power receiving circuit 204. Here, the SWcircuit 106 and the power receiving circuit 204 are formed fromresonance power source circuits including an inductance and a capacitor.The element values of the resonance power source circuits are determinedaccording to inductance values and resistance values of the powertransmitting coil 101 and the power receiving coil 201, the couplingcoefficient of the power transmitting coil 101 and the power receivingcoil 201, the switching frequency, the maximum power source outputvoltage value, the maximum motor application voltage value (voltagevalue applied to the motor 400), and the resistance value of the motor400. The power source output voltage value and the motor applicationvoltage value change each time depending on the command from thecontroller 103. Thus, the element values of the resonance power sourcecircuits can be adjusted so that the power source output voltage valueand the motor application voltage value are substantially equal within avoltage range that is determined beforehand in accordance with the use.Furthermore, the motor 400 can be driven with high accuracy by adoptinga configuration such that the relationship between the power sourceoutput voltage value and the motor application voltage value is measuredin advance and made into a table, and a command is issued for the powersource output voltage value for obtaining the desired motor applicationvoltage value.

The electromagnetic coupling in the present embodiment includes bothelectric field coupling and magnetic field coupling. That is, thewireless power transmission may be performed via electric fieldcoupling, via magnetic field coupling, or via both electric fieldcoupling and magnetic field coupling. Magnetic field coupling includeselectromagnetic induction and magnetic resonance. Also, the wirelesspower transmission may be performed according to a method utilizingmicrowaves. Note that, in the present embodiment, a case in whichwireless power transmission utilizing magnetic field coupling isperformed will be mainly described.

The clock signal generated by the SW circuit 106 is also used forsynchronous rectification by the motor driving circuit 206. The clocksignal output from the SW circuit 106 and the sign switching signaloutput from the controller 103 are input to the transmitting circuit105, and signals for transmission with adjusted phase and amplitude aregenerated. Then, the transmission signals are input to the transmittingcoupler 102. Note that the transmitting circuit 105 may generate atransmission signal from either the clock signal or the sign switchingsignal. The phase is adjusted in order to adjust the timing ofsynchronous rectification, and the amplitude is adjusted forreproduction by the receiving circuit 203. Then, the transmissionsignals are transmitted to the receiving coupler 202 via theelectromagnetic coupling between the transmitting coupler 102 and thereceiving coupler 202, and are input to the receiving circuit 203. Theclock signal is transmitted in a streaming-like manner via theelectromagnetic coupling. Thus, a delay that would occur in wirelesscommunication such as that in which packets are transmitted does notoccur, and high-speed signal transmission can be performed. Thereceiving circuit 203 reproduces the clock signal from a signal receivedby the receiving coupler 202. The reproduced clock signal is input tothe gate driving circuit 205, and drives a synchronous rectificationcircuit 207 (FIG. 2 ) of the motor driving circuit 206. The accuracy ofmotor control is increased by providing a synchronous rectificationcircuit because even a small voltage of several mV that cannot berectified by a diode can be rectified and a small voltage can be appliedto a motor. The motor driving circuit 206 rectifies the AC waveformoutput from the power receiving circuit 204, and then determines thesign of the output voltage and applies the output voltage to the motor400.

The wireless communication between the transmitting coupler 102 and thereceiving coupler 202 may be performed via electric field coupling, viamagnetic field coupling, or via both electric field coupling andmagnetic field coupling. The wireless communication in the presentembodiment, which is performed via electromagnetic coupling, differsfrom radiative communication methods utilizing far-field electromagneticwaves as the transmission medium, and is a non-radiative communicationmethod utilizing a near electromagnetic field as the transmissionmedium. Note that, in the present embodiment, electric signals arewirelessly transmitted between the transmitting coupler 102 and thereceiving coupler 202 according to a baseband method. According to thebaseband method, the modulation and demodulation of electric signals arenot necessary, and thus, the circuit scale can be reduced andcommunication can be performed with little delay. However, thecommunication method is not limited to this, and for example, carriercommunication may be performed by modulating a carrier wave transmittedfrom the transmitting coupler 102 to the receiving coupler 202 using acontrol signal or a clock signal.

FIG. 2 is a diagram illustrating circuit configurations of a motordriving circuit and a gate driving circuit according to the firstembodiment. It illustrates an example of detailed circuit configurationsof the motor driving circuit 206 and the gate driving circuit 205 in thepresent embodiment. The motor driving circuit 206 includes thesynchronous rectification circuit 207 and a sign switching circuit 208.The gate driving circuit 205 includes driving signal generation circuits215-1 to 215-8. The synchronous rectification circuit 207 operates usinggate driving signals generated by the driving signal generation circuits215-1 to 215-4 based on the clock signal output from the receivingcircuit 203. Specifically, the driving signal generation circuits 215-1to 215-4 generate, as gate driving signals, source-gate voltages(signals) of switching elements of the synchronous rectification circuit207. The source-gate voltages can be generated by insulating thereceiving circuit 203 and the motor driving circuit 206 from one anotheror by using a bootstrap circuit. The switching elements of thesynchronous rectification circuit 207 are turned on and off by thesource-gate voltages. For example, the upper side of the output from thesynchronous rectification circuit 207 would constantly have a positivepotential by turning on the upper left and lower right switchingelements of the synchronous rectification circuit 207 and turning offthe lower left and upper right switching elements when the upper one ofthe two terminals of the clock signal input illustrated in FIG. 2 has apositive potential, and doing the reverse when the upper terminal of theclock signal input has a negative potential. With regard to the timingsfor performing this switching between on and off, it suffices to measurethe zero-crossing timings of the output voltage waveform of the powerreceiving circuit 204 in advance, and to perform phase adjustment usingthe transmitting circuit 105 so that the phase of the clock signalmatches the zero-crossing timings. It suffices to keep the phase shiftamount fixed after the adjustment. In addition, if the zero-crossingtimings fluctuate depending on the output voltage amplitude of the powersource 104, rectification efficiency can be increased to a furtherextent by measuring the relationship between the output voltageamplitude and the phase shift amount in advance, and automaticallycorrecting the phase shift amount in relation to the output voltageamplitude in the power transmitting-side circuit 100.

The sign switching circuit 208 is a circuit that selects whether todirectly output the output voltage of the synchronous rectificationcircuit 207 as a positive voltage or to output the output voltage afterswitching the voltage to a negative voltage. The switching elements ofthe sign switching circuit 208 operate according to gate driving signalsgenerated by the driving signal generation circuits 215-5 to 215-8 basedon the sign switching signal output from the controller 103. Similarlyto the synchronous rectification circuit 207, the driving signalgeneration circuits 215-5 to 215-8 generate, as gate driving signals,source-gate voltages (signals) of the switching elements of the signswitching circuit 208. Similarly to the synchronous rectificationcircuit 207, the source-gate voltages can be generated by insulating thereceiving circuit 203 and the motor driving circuit 206 from one anotheror by using a bootstrap circuit. If a positive voltage is to be appliedto the motor 400, it suffices for the controller 103 to transmit a signswitching signal that turns on the upper right and lower left switchingelements of the sign switching circuit 208 and turns off the upper leftand lower right switching elements.

Operation of Driving System 300 for Application of Negative Voltage toMotor

Next, an example of an operation of the driving system 300 for applyinga negative voltage to the motor 400 will be described. The sign of thesign switching signal transmitted from the controller 103 to thetransmitting circuit 105 is inverted, but otherwise the operation is thesame as that for applying a positive voltage. If the sign of the signswitching signal is inverted, the switching elements of the signswitching circuit 208 that turn on and the switching elements that turnoff switch with one another. Accordingly, the upper left and lower rightswitching elements of the sign switching circuit 208 turn on and thelower left and upper right switching elements turn off, and the sign ofthe motor application voltage is inverted.

As described above, the signals that control the motor driving circuit206 include a clock signal with a fixed frequency and duty and a simpleon/off signal that provides timings for switching the sign of the outputvoltage. Conventionally, a typical motor control signal is a pulse widthmodulation (PWM) signal, the amplitude of the voltage input to the motordriving circuit is fixed, and the amplitude and sign of the motorapplication voltage are changed by changing the pulse width of thecontrol signal provided to the motor driving circuit. On the other hand,in the present embodiment, the amplitude of the motor applicationvoltage is changed by the power source 104 of the powertransmitting-side circuit 100. Thus, the power receiving-side circuit200, the space for which is limited, does not need to change theamplitude of the motor application voltage, and a reduction in the sizeof the power receiving-side circuit 200 is realized.

FIG. 3 is a schematic diagram illustrating an example in which thedriving system 300 is applied to a movable stage, for example, of asemiconductor exposure device., according to one embodiment. The powerreceiving-side circuit 200 is arranged on a movable stage 401, and movesphysically relative to the power transmitting-side circuit 100. Thepower transmitting-side circuit 100 is not arranged on the movable stage401, and instead, is arranged on the stationary side, in which a movablestage power source 402 that moves the movable stage 401 is arranged. Thepower transmitting-side circuit 100 itself does not move.

A power transmitter 110 and a power receiver 210 for wireless powersupply and communication are present between the power transmitting-sidecircuit 100 and the power receiving-side circuit 200. The powertransmitting coil 101 and the transmitting coupler 102 are mounted onthe power transmitter 110, and the power receiving coil 201 and thereceiving coupler 202 are mounted on the power receiver 210. The powertransmitter 110 and the power receiver 210 are not in contact with oneanother. The power receiver 210 is also arranged on the movable stage401, and moves along with the movable stage 401. For example, the powertransmitter 110 is longer than the power receiver 210, and the powerreceiver 210 is configured to be capable of uniaxially moving in thedirection along which the power transmitter 110 is longer than the powerreceiver 210. By making the power transmitter 110 long enough to coverthe movement range of the movable stage 401 in such a manner, power canbe supplied to the motor in a contactless manner regardless of theposition to which the movable stage 401 moves. Note that the arrangementof the power transmitter 110 and the power receiver 210 is not limitedto that illustrated in FIG. 3 , and the power receiver 210 may beconfigured to be longer than the power transmitter 110. In addition, thepower transmitter 110 may move relative to the power receiver 210, orthe power transmitter 110 and the power receiver 210 may both moverelative to one another along a predetermined direction. In order toallow the power transmitter 110 to move, the power transmitter 110 maybe installed on a different movable stage.

The power transmitting coil 101 has the shape of an elliptical coil thatis longer sideways, for example, and the power receiving coil 201 is acoil that is shorter than the power transmitting coil 101. The powerreceiving coil 201 may be long and the power transmitting coil 101 maybe short. The transmitting coupler 102 is constituted by longdifferential signal wires arranged on a printed circuit board, forexample, and the clock signal is input from ends thereof on one side,and the ends thereof on the other side are terminated. The receivingcoupler 202 is constituted by short differential signal wires arrangedon a printed circuit board, for example. The differential signal wiresare connected to differential inputs of the receiving circuit 203.Signals are transmitted via the differential signal wires of thetransmitting coupler 102 and the receiving coupler 202 facing oneanother and electromagnetically coupling with one another. The receivingcoupler 202 may be long and the transmitting coupler 102 may be short.

FIG. 4 shows measurement results of input/output characteristics of thedriving system according to the first embodiment. FIG. 4 showsmeasurement results (solid lines) of input/output characteristicsobtained by measuring application voltages applied to the motor 400relative to output voltages of the power source 104. In the graphs 4 aand 4 b, the horizontal axis indicates output voltages of the powersource 104, i.e., input voltages, and the vertical axis indicatesapplication voltages applied to the motor 400, i.e., output voltages.Both positive and negative voltages are measured by reversing the signswitching signal. In addition, an ideal curve (broken line)corresponding to the case in which the input and output match is alsoillustrated in the graphs. The switching frequency is 4 MHz, and a 3 mHinductor is connected as a dummy load in place of a motor. It can beseen from the graph 4 b that any voltage from 0 V to 30 V can bewirelessly supplied. While there are parts where the output voltage islower than the ideal curve, the output voltage can be made closer to theideal curve by correcting the command value of the output voltageamplitude from the controller 103 to the power source 104 so as toincrease the power source output voltage by the amount by which theoutput voltage is lower than the ideal curve, based on the graphs 4 aand 4 b.

The first embodiment has been described above. According to variousembodiments of the above described first embodiment, an increase in thespeed of motor control is realized by transmitting a motor drivingsignal to the movable side in a contactless manner using electromagneticcoupling. Furthermore, a high-speed clock signal can also be transmittedto a synchronous rectification circuit with little delay. Thus, adetection circuit and a feedback control circuit become unnecessary onthe movable side, and a reduction in the size and weight of themovable-side circuit is realized.

Second Embodiment

Next, the driving system 300 in the second embodiment will be described.Differences from the first embodiment will be described in the followingdescription. Redundant description thereof has been omitted whereappropriate. FIG. 5 is a diagram illustrating circuit configurations ofthe motor driving circuit and the gate driving circuit according to asecond embodiment. FIG. 5 illustrates an example of detailed circuitconfigurations of the motor driving circuit 206 and the gate drivingcircuit 205 in the present embodiment. In the first embodiment, thesynchronous rectification circuit 207 and the sign switching circuit 208are configured to be separate. However, in the present secondembodiment, the synchronous rectification circuit 207 and the signswitching circuit 208 are combined into a combined circuit (synchronousrectification/sign switching circuit 209). Due to this factor, the scaleof the gate driving circuit 205 is halved, and a further reduction incircuit size is realized.

The switching elements of the synchronous rectification/sign switchingcircuit 209 operate using gate driving signals generated by the drivingsignal generation circuits 215-9 to 215-12. The driving signalgeneration circuits 215-9 to 215-12 generate, as gate driving signals,source-gate voltages (signals) of the switching elements of thesynchronous rectification/sign switching circuit 209. Similarly to thefirst embodiment, the source-gate voltages are generated by insulatingthe receiving circuit 203 and the motor driving circuit 206 from oneanother or by using a bootstrap circuit.

The switching elements are arranged in the form of bidirectionalswitches in which there are two switching elements per driving signalgeneration circuit (any one of the driving signal generation circuits215-9 to 215-12). The reason for this is because an AC voltage entersfrom the input, and thus, if there was only one switching element, thebody diode would turn on when the sign is inverted and the gate drivingcircuit 205 would not be able to perform on/off control.

In addition, in order to perform synchronous rectification and signswitching simultaneously using a single circuit, the control signal thatis input to the gate driving circuit 205 is a signal in which the clocksignal and the sign switching signal are combined. In the firstembodiment, the clock signal and the sign switching signal are separatesignals, and thus, two pairs of the transmitting coupler 102 and thereceiving coupler 202 are necessary, one for the clock signal and theother for the sign switching signal. On the other hand, in the presentembodiment, one pair of the transmitting coupler 102 and the receivingcoupler 202 suffices, and the size of the power transmitter 110 and thepower receiver 210 can be reduced.

Next, the operation of the synchronous rectification/sign switchingcircuit 209 will be described. During the application of a positivevoltage to the motor 400 (during the output of a positive voltage), itsuffices to turn on the upper left and lower right bidirectionalswitches of the synchronous rectification/sign switching circuit 209 andturn off the lower left and upper right bidirectional switches when theupper one of the two terminals of the input has a positive potential,and to switch to the reverse when the upper one of the two terminals ofthe input switches to having a negative potential. Similarly to thefirst embodiment, this is realized by providing gate driving signalssynchronized with the switching clock of the SW circuit 106. Here, ifthe switching elements were not in the form of bidirectional switches,the body diode would turn on at the point in time when the upper one ofthe two terminals of the input switches to having a negative potential,and it would be impossible to perform synchronous rectification.

Furthermore, when applying a negative voltage to the motor 400 (whenswitching the output to a negative voltage), it suffices to invert thesynchronized gate driving signals. That is, it suffices to turn on thelower left and upper right bidirectional switches of the synchronousrectification/sign switching circuit 209 and turn off the upper left andlower right bidirectional switches when the upper one of the twoterminals of the input has a positive potential, and to switch to thereverse when the upper one of the two terminals of the input switches tohaving a negative potential. The control signal input to the gatedriving circuit 205 can realize synchronous rectification and signswitching using a single circuit if the above-described conditions aresatisfied.

It suffices to generate such a control signal using the transmittingcircuit 105. The above-described conditions are satisfied if the clocksignal input from the SW circuit 106 and the sign switching signal inputfrom the controller 103 are synthesized by exclusive ORing, for example.The clock signal is directly transmitted when the sign switching signalis “0”, and the clock signal is transmitted in an inverted state if thesign switching signal is “1”. The other parts are the same as those inthe first embodiment.

Synchronous rectification and sign switching can be realized using asingle circuit in such a manner because the signals that control themotor driving circuit 206 include a clock signal having a fixedfrequency and duty and a simple on/off signal that provides timings forswitching the sign of the output voltage, as described above. Thetypical motor control signal disclosed in the prior art is a PWM signal,which is of a completely different waveform from the clock signal forsynchronous rectification. For this reason, the synchronousrectification circuit cannot be controlled and the scale of the gatedriving circuit cannot be reduced with a PWM signal, and thus thereduction in size realized by various embodiments of the presentdisclosure cannot be realized with a PWM signal.

FIG. 6 shows actually-measured results of operation waveforms of thedriving circuits according to the second embodiment. In FIG. 6 , thewaveforms 6 a show actually-measured waveforms indicating therelationship between the sign switching signal output by the controller103, the control signal input to the gate driving circuit 205, and theapplication voltage applied to the motor 400, and the waveforms 6 b showenlarged waveforms of the waveforms 6 a. The horizontal axis indicatestime, and the waveforms 6 a and the waveforms 6 b respectivelycorrespond to 5 μs/div and 200 ns/div. The waveforms 6 a and 6 b bothshow the sign switching signal waveform, the control signal waveform,and the application voltage waveform in order from the top. The verticalaxis indicates voltage, and the sign switching signal, the controlsignal, and the application voltage are indicated in 2 V/div, 4 V/div,and 2 V/div, respectively. The application voltage waveform is anegative voltage before it rises and a positive voltage after it rises.The switching frequency is 4 MHz, and a 3 mH inductor is connected as adummy load in place of a motor.

From FIG. 6 , it can be seen that, when the sign switching signalswitches from “1” to “0”, the control signal input to the gate drivingcircuit 205 is inverted, i.e., the phase of the waveform of thesynthesized signal synthesized from the clock signal and the signswitching signal is inverted, and the application voltage waveformswitches from a negative voltage to a positive voltage. While it takesabout 10 μs to switch from a negative voltage to a positive voltage, thetime constant defined by an output capacitor and an inductor of thedummy load is related to this, and speed can be further increased bymaking the output capacitor smaller.

In addition, it can be confirmed from FIG. 6 that the delay time fromthe timing when the sign switching signal switches from “1” to “0” untilwhen the phase of the control signal waveform input to the gate drivingcircuit 205 is inverted is equal to or shorter than 100 ns. That is,motor operation can be controlled at a cycle equal to or shorter than100 ns. This is because the control signal is transmitted between thetransmitting coupler 102 and the receiving coupler 202 viaelectromagnetic coupling with a delay of only several ns, and motoroperation cannot be controlled at such a short cycle if wirelesscommunication utilizing electromagnetic waves is used as in theconventional technique. In addition, a clock signal that switches at ahigher speed than motor control cannot be transmitted with little delay,and thus, a synthesized signal synthesized from a clock signal and asign switching signal cannot be transmitted. That is, in a case in whichwireless communication utilizing electromagnetic waves is used, the sizeof the gate driving circuit 205 cannot be reduced by combining thesynchronous rectification circuit 207 and the sign switching circuit 208as in the present embodiment. An increase in the speed of motor controland a reduction in the size and weight of a circuit arranged on themovable side are realized by transmitting a control signal viaelectromagnetic coupling as in the present embodiment.

Note that, while the synchronous rectification/sign switching circuit209 in FIG. 5 is described as a full bridge-type circuit, thesynchronous rectification/sign switching circuit 209 may be a centertap-type circuit. In such a case, wiring becomes complex because thepower receiving coil 201 would need to be configured into a centertap-type coil. However, the number of switching elements in thesynchronous rectification/sign switching circuit 209 can be reduced tofour.

Modifications

In the above-described embodiments, a case in which the transmittingcoupler 102 and the receiving coupler 202 are coupled by electromagneticcoupling is described. However, in other embodiments, the transmittingcoupler 102 and the receiving coupler 202 may be coupled by opticalcoupling. It suffices to arrange a laser or a light-emitting diode withsharp directivity on the stationary side and make the laser orlight-emitting diode emit light along the movement direction of thestage, and to arrange a light-receiving element such as a photodiode onthe movable side so that the light-receiving surface is positioned onthe optical path of the emitted light, for example. While opticalcoupling also enables transmission to be performed with less delaycompared to wireless communication utilizing electromagnetic waves,there is a delay that is dependent on the frequency characteristics ofthe light-emitting element and the light-receiving element when comparedto electromagnetic coupling.

Also, the power for causing the receiving circuit 203 and the gatedriving circuit 205 to operate may be generated from the motorapplication voltage using a buck-boost circuit, etc., or a powertransmitting coil and a power receiving coil may be separately provided,for example.

Also, the power transmitting coil 101 and the power receiving coil 201may be formed by wires on the printed circuit boards. Furthermore,magnetic sheets may be affixed onto the printed circuit boards to reduceloss during electromagnetic coupling. In addition, the powertransmitting coil 101 and the power receiving coil 201 may be awire-wound transformer in which a magnetic body of ferrite, etc., and awinding of a litz wire, etc., are used, for example.

Also, in a case in which the absolute value of the minimum voltage to beapplied to the motor 400 is equal to or greater than several hundreds ofmV and can be rectified with a diode, the synchronous rectificationcircuit 207 may be a rectification circuit in which a diode is used. Insuch a case, gate driving of the synchronous rectification circuit 207is unnecessary, and the size of the power receiving-side circuit 200 canbe reduced.

According to the above-described embodiments, the speed of wirelesscommunication of control signals for driving a load portion can beincreased. The invention is not limited to the above-describedembodiments, and various changes and modifications are possible in otherembodiments of the present disclosure.

While exemplary embodiments have been described, it is to be understoodthat the present disclosure is not limited to the disclosed exemplaryembodiments. The scope of the following claims is to be accorded thebroadest interpretation so as to encompass all such modifications andequivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2019-097072, filed May 23, 2019, which is hereby incorporated byreference herein in its entirety.

1. A control system comprising: a power transmitting coil for wirelesslytransmitting power supplied from a power source; a power receiving coilfor wirelessly receiving power by electromagnetic coupling between thepower transmitting coil and the power receiving coil; a driving circuitconfigured to drive a load portion using the power received via thepower receiving coil; a transmitting coupler for wirelessly transmittinga transmission signal generated based on a clock signal which is usedfor synchronous rectification for controlling the driving circuit; areceiving coupler for wirelessly receiving the transmission signal byelectromagnetic coupling between the transmitting coupler and thereceiving coupler; and a generation circuit configured to generate adriving signal for controlling the driving circuit from the transmissionsignal received via the receiving coupler.
 2. The control systemaccording to claim 1, wherein the control system includes a powertransmitter and a power receiver, the power transmitter includes thepower transmitting coil and the transmitting coupler, and the powerreceiver includes the power receiving coil and the receiving coupler. 3.The control system according to claim 2, further comprising a movableportion that relatively moves at least one of the power transmitter andthe power receiver along a predetermined direction.
 4. The controlsystem according to claim 1, further comprising a converter circuit thatconverts a DC voltage output from the power source into an AC voltageusing the clock signal, and applies the AC voltage to the powertransmitting coil, wherein the transmission signal wirelesslytransmitted via the transmitting coupler includes the clock signal, andthe driving signal generated by the generation circuit includes a signalthat corresponds to the clock signal and that is for performingsynchronous rectification in the driving circuit.
 5. The control systemaccording to claim 4, wherein the clock signal is generated by theconverter circuit.
 6. The control system according to claim 4, whereinthe driving circuit includes a synchronous rectification circuit thatreceives a voltage output from the power receiving coil as an inputvoltage, and a sign switching circuit that switches a sign of thevoltage output from the synchronous rectification circuit, and thegeneration circuit generates a driving signal for the synchronousrectification circuit from the clock signal included in the transmissionsignal, and generates a driving signal for the sign switching circuitfrom a signal for sign switching included in the transmission signal. 7.The control system according to claim 4, wherein the driving circuitincludes a combined circuit in which a synchronous rectification circuitthat receives a voltage output from the power receiving coil as an inputvoltage and a sign switching circuit that switches a sign of the voltageoutput from the synchronous rectification circuit are combined, and thegeneration circuit generates a driving signal for the combined circuitfrom the clock signal and a signal for sign switching, which areincluded in the transmission signal.
 8. The control system according toclaim 7, wherein the transmission signal is a signal synthesized byexclusive ORing the signal for sign switching and the clock signal. 9.The control system according to claim 1, wherein the driving circuit isconfigured as a full bridge-type circuit in which a plurality ofswitching elements are used.
 10. The control system according to claim9, wherein the plurality of switching elements are arranged in the formof bidirectional switches.
 11. The control system according to claim 1,wherein the driving circuit is configured as a center tap-type circuitin which a plurality of switching elements are used.
 12. The controlsystem according to claim 1, wherein wireless communication between thetransmitting coupler and the receiving coupler is performed inaccordance with a baseband method.
 13. A control system comprising: apower transmitting coil for wirelessly transmitting power supplied froma power source; a power receiving coil for wirelessly receiving power byelectromagnetic coupling between the power transmitting coil and thepower receiving coil; a driving circuit configured to drive a loadportion using the power received via the power receiving coil; atransmitting coupler for wirelessly transmitting a transmission signalgenerated based on a clock signal which is used for synchronousrectification for controlling driving of the driving circuit; areceiving coupler for wirelessly receiving the transmission signal byoptical coupling between the transmitting coupler and the receivingcoupler; and a generation circuit configured to generate a drivingsignal for controlling the driving circuit from the transmission signalreceived via the receiving coupler.
 14. A control method for a controlsystem including a power transmitting coil, a power receiving coil, atransmitting coupler, a receiving coupler, and a load portion, thecontrol method comprising: wirelessly transmitting power supplied from apower source via electromagnetic coupling between the power transmittingcoil and the power receiving coil; wirelessly transmitting atransmission signal generated based on a clock signal which is used forsynchronous rectification for controlling driving of the load portionvia electromagnetic coupling between the transmitting coupler and thereceiving coupler; and generating, from the transmission signal receivedvia the receiving coupler, a driving signal for controlling a drivingcircuit that drives the load portion using the power received via thepower receiving coil.
 15. The control method according to claim 14further comprising relatively moving at least one of a power transmitterand a power receiver that are included in the control system along apredetermined direction, wherein the power transmitter includes thepower transmitting coil and the transmitting coupler, and wherein thepower receiver includes the power receiving coil and the receivingcoupler.
 16. The control method according to claim 14 furthercomprising: converting a DC voltage output from the power source into anAC voltage using the clock signal; and applying the AC voltage to thepower transmitting coil, wherein the transmission signal wirelesslytransmitted via the transmitting coupler includes the clock signal, andwherein the generated driving signal includes a signal that correspondsto the clock signal and that is for performing synchronous rectificationin the driving circuit.